1. Field of the Invention
The present invention relates to projection screens, and more particularly to high speed rotating lenticular screens adapted to be rotated during projection to produce an enlarged exit pupil.
2. DESCRIPTION OF THE PRIOR ART
Moving projection screens are well known and are generally classified in class 350, subclasses 117 and 120 under moving projection screens. The prior art moving screens include projection screens having corrugations and/or protrusions as shown in U.S. Pat. No. 1,864,946. Such screens produce an image thereon which appears to have depth.
Prior art moving screens also include reflective screens having a plurality of curved surfaces which reflect light rays of a projected image. Such reflective screens as shown in U.S Pat. No. 2,132,904 tend to produce a three dimensional image effect.
Heretofore, moving Fresnel or lenticular lenses have been employed in projection systems either in front of or behind a diffussion screen or with no screen at all. When the projected image to be made visible to the observer is formed in or near the plane of the lens the motion of the lens has no effect upon the formation of the image and there is a secondary effect in that the exit pupil or cone of vision projected through or from the lens is enlarged. Typical of such teachings in the prior art are U.S. Pat. No. 2,583,373 and British Pat. No. 1,275,917.
Heretofore, prior art moving screen projection apparatus has in general provided high inertia low speed moving screens. Flexible endless belt screens have been employed over rollers, while rigid lens and screens have been orbited or revolved. None of the prior art moving screens have been extremely simple in design, low in cost and high in quality and brilliance and resolution. Some prior art screens have been curved to aid in compensating for distortion introduced by large angles deviating from a normal optical path.
Heretofore rotary screen projection apparatus has been expensive and unduly large. Such expensive rotary screen projection devices are difficult to assemble or service and their application has been restricted to expensive medical and scientific laboratory applications.